How to connect High(ish) Power LED (Begginer need help)

Hi guys

I am new to Arduino and electronics so I am sorry if my questions are stupid.

I want to connect some high power LED 120mA, I have read that the pro mini can only power 20-40mA.

If I take the positive direct to the LED through a resister and then switch the ground by making one of the digital pins Low. will this be OK?

Thanks loads in anticipation

Rich

No, you need a transistor, and preferably a constant current LED driver to keep your LED from overheating and burning up.

rjmiller: If I take the positive direct to the LED through a resister and then switch the ground by making one of the digital pins Low. will this be OK?

How do you imagine that would turn 30 mA into 120 mA?

Paul__B: How do you imagine that would turn 30 mA into 120 mA?

I guess the OP though that the 40mA limit applies only to sourcing current and did not realise this also applies to sinking current. The OP was hoping that the limit for sinking current was much higher.

I was waiting for him to come back with something fantastical. :roll_eyes:

Never mind.

I was then going to point out what the “C” in “CMOS” means.

Paul__B: How do you imagine that would turn 30 mA into 120 mA?

With four pins.

(hey, you asked)

Chagrin: With four pins.

Actually, two pins each from 2 different ports, otherwise you would exceed the 100mA per port limit.

Paul__B: How do you imagine that would turn 30 mA into 120 mA?

You had on opportunity to explain to someone who does not understand. An opportunity to teach. An opportunity to teach to the exact audience for which an Arduino is intended. Wow. You failed spectacularly.

What is especially sad is that someone extended that courtesy to you. You were not born understanding. Someone took the time to teach you.

@CrossRoads, @PaulRB, and @Chagrin, thank you for your replies.